Looks like an earthquake just woke everyone up in the San Francisco bay area.The United States Geological Survey is reporting that it was a 4.3-magnitude earthquake.As a side note, it looks like we're getting back to the basics of what Twitter is actually best for: live reporting earthquakes in Silicon Valley.One Twitter user wrote shortly afterward, "All of San Francisco just woke up, tweeted, and are now going back to bed for an hour. Thanks early morning #earthquake."Another wrote, "Not even my guitar on the wall moved" during the quake.The shaking from the San Francisco earthquake was felt within a 60-mile radius, from Santa Rosa in the north to Santa Cruz in the south. The epicenter was a mile from East Richmond Heights, two miles from Richmond, four miles from Berkeley and 13 miles from San Francisco City Hall.